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Old 06-10-2019, 09:38 PM
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Crankyolman Crankyolman is offline
327 Rambler
Join Date: Sep 27, 2017
Location: Pacific Northwest
Posts: 609
I thought I'd update you guys on this.

It's been a while since I put this on. I have most of it dialed in but I'm still working on getting the prim shot dialed in. Otherwise it's running real nice.

Some of the things I have learned is that it may start and run right out of the box but there are things you have to do after that.

To begin with almost everybody needs to adjust the IAC step, which is basically the butterflies that let air in at idle. IAC step should be 3 to 10 but many people are happy with up to 15. Out of the box mine was set at 82 so I had to turn the screw that opens the throttle quite a bit, which gives the engine more air at idle and brings the IAC step down. Once that is done you just drive it around for a bit. Mine took probably 100 miles before it dialed itself in for the most part.

Another important thing is you need to buy a fuel pressure gauge for tuning purposes so you can adjust PWM, which has something to do with the fuel pump. In my case preset PWM was too high and actually caused some problems. With the fuel pressure gauge you adjust PWM down until the fuel pressure begins to drop then turn it up a little bit. I actually reduced PWM from a preset of 80 down to 66 without any pressure drop. This fixed the fuel issue it had although I'm not really sure what it did but it got everything where it should be.

The last really important thing is air. I have always gone to great lengths to keep my truck as stock as I can. I have made some compromises like HEI ignition and some other minor things and plan on upgrading the alternator. I've never really cared for open air filters. I like the look of the stock air filter but always thought it looked unbalanced and like the look of a dual snorkel. Well as luck would have it I go the opportunity to convert my air filter to a dual snorkel and noticed some changes instantly which is something I wasn't expecting. The engine runs smoother and is quieter. Sometimes at stop signs I have to look at the tach to make sure it's still running. On the controller also showed signs that it made a difference.

The only conclusion I can make from this is the early single snorkel is too restrictive for the Fitech injectors. Adding the 2nd one allows the system to breath how it needs to.

Right now everything is tuned and running well and I'm quite happy with it.
'72 J4500
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